One scene from Angel in particular comes to mind from "The Prodigal" :

Darla: “This contest is ended, is it?”
Angel has his feet up on the table playing with his father’s pipe. His family lies dead around him.
Angel: “Now I’ve won.”
Darla: “You’re sure?”
Angel puts his feet down and picks up a mug of ale: “Of course. I proved who had the power here.”
Darla: “You think?”
Angel: “What?”
Darla: “You’re victory over him took but moments.”
Angel looks over at the body of his father and gets up: “Yes?”
Darla: “But his defeat of you will last life times.”

menomegirl, I think the fact that of the two characters who appear in both the first and last episodes, one orders the other's death, underscores the failure of family in Angel. Come to think of it, I don't think there are any other TV shows where that happens.

And Dalton, I agree that that scene is pretty key in understanding all the issues Angel faces when trying to start a family.